LONDON (Reuters) - Four high street banks, HSBC, Lloyds, TSB and Allied Irish Bank (AIB), broke Britain's competition rules, the Competition and Markets Authority said in a statement on Thursday.

It did not set out any financial penalties for the breaches, which covered various sections of the Retail Banking Order that sets out banks' obligations to inform customers about their products and services.

The banks were issued with a letter informing them of the breaches. Lloyds, AIB and TSB have confirmed they are making changes to their operations to prevent further breaches, the CMA said.

HSBC was considered to have breached the rules more extensively and has been issued with details of an action plan to ensure future compliance, the CMA added.